Field of Use
This invention relates to filament winding and, more particularly, to filament wound tubes that are connectable with each other. This invention, still more particularly, relates to connecting tubes that are adapted to transmit torsional as well as radial and axial forces and, accordingly, are useful in oil field drilling pipe, drive shafts for transmitting rotary power and suspension components for heavy ground vehicles.
Filament winding is a well known technique for making composite tubes using high strength filaments such as carbon (graphite) fiber and thermosettable resin. Compared to tubes made of metal such as steel, the resultant filament wound tubes are considerably lighter in weight, have equivalent strength and generally have better fatigue resistance. Moreover, the tubes do not corrode.
When a composite tube is to be used in a torque transmitting application, however, the tube needs to be connected to another body. A variety of connectors have been proposed in the prior art including, for example, the use of rivets, pins and the like which are inserted through holes drilled in the pipe.
Cutting holes in a composite tube is not always advantageous. For example, in oil field drilling pipe, the tube needs to be impermeable to highly pressurized fluids and effective sealing of the holes in the pipe is difficult. Moreover, when significant torsion and bending loads are applied to the tubes having such pins, rivets and the like, these fasteners undergo significant loads and may break or otherwise cause excessive wear around the holes in the composite tube.